1. Field of the Invention
The present invention relates to an image display apparatus, and also to a three-dimensional image display apparatus and a three-dimensional image display system in which a calculated interference fringe (computer generated hologram) is used to display a three-dimensional image.
2. Description of the Related Art
Conventionally known are image display apparatuses for displaying an image which is formed in a light modulation device by applying a voltage to the light modulation device. Such image display apparatuses include a liquid crystal display (LCD), for example.
Here, the light modulation device is a device having an electro-optic effect. The electro-optic effect is a phenomenon caused by applying an electric field to a substance, and specifically, is a phenomenon in which the refractive index of a substance changes according to the electric field intensity applied to the substance.
Referring to FIGS. 1(a), 1(b), 2(a), and 2(b), an image display apparatus using a conventional light modulation device will be described. Known as the image display apparatus using the conventional light modulation device is an image display apparatus having a simple matrix electrode structure shown in FIGS. 1(a) and 1(b) and an image display apparatus having an active-matrix electrode structure shown in FIGS. 2(a) and 2(b).
As shown in FIG. 1(a), in the image display apparatus having the simple-matrix electrode structure, electrodes 23 are provided in an X-axis direction on the top surface of a thinned light modulation device 25 and electrodes 24 are provided in a Y-axis direction on the bottom surface of the thinned light modulation device 25.
Each of the intersections between the electrodes 23 in the X-axis direction and the electrodes 24 in the Y-axis direction corresponds to a pixel electrode 23a corresponding to each pixel constituting an image to be displayed by the image display apparatus having the simple matrix electrode structure, as shown in FIG. 1(b).
On the other hand, as shown in FIG. 2(a), in the image display apparatus having the active-matrix electrode structure, plural electrodes 23 are provided on the top surface of a light modulation device 25 and an electrode 24 is provided on the bottom surface of the light modulation device 25.
As shown in FIG. 2(b), each of the electrodes 23 has plural pixel electrodes 23a corresponding to each pixel constituting an image to be displayed by the image display apparatus having the active-matrix electrode structure. It is configured that a transistor which can be turned on and off independently is provided for each pixel electrode 23a. The electrode 24 is grounded.
In the conventional image display apparatuses having the simple matrix electrode structure or the active-matrix electrode structure, a voltage value to be applied to each pixel electrode 23 is controlled based on the gray-scale value of each pixel constituting an image to be recorded in the light modulation device 25.
However, in the conventional image display apparatuses having the simple matrix electrode structure or the active-matrix electrode structure, since a voltage value to be applied can be changed only on a pixel-electrode-23a basis, a rectangular region (pixel) shown in FIG. 3 has the same gray-scale value.
Thus, there is a problem in that the precision of images which can be displayed by the conventional image display apparatus is limited by the size and shape of each pixel electrode 23a. 
In other words, the conventional image display apparatus has a problem in that since the miniaturization of the pixel electrodes 23a is limited, a quantization error in an image to be displayed becomes large, making it impossible to display the image with high precision.
Further, the conventional image display apparatuses have a problem in that crosstalk caused by voltages to be applied to pixel electrodes 23a is generated between adjacent pixels (rectangular regions).